It is well known in the literature that Polyunsaturated Fatty Acids (PUFAs) of all types are highly susceptible to peroxide, free radical and light induced degradation including rancification and polymerization making them unsuitable for human consumption. For example, it is well known that flax seed oil, also known as linseed oil, readily undergoes free radical oxidation to advantageously form polymeric surfaces including oil based paints, hard furniture finishes and linoleum flooring. In addition, many companies offer flax seed oil for human consumption as a dietary supplement or food ingredient because of the high levels of PUFAs found in raw flax seed and its expeller pressed oils and more particularly Alpha-Linolenic Acid (ALA) and Linolenic Acid (LA). Many flax seed oil product labels suggest that the product must be refrigerated at all times due to the instability of such PUFAs in flax seed oil. Careful examination of the majority of commercially available flax seed oils obtained by expeller pressing, including those typically stored under refrigerated conditions, unfortunately reveals that they are unfit for human use based on their measured Peroxide Values (PVs). Such PV values above 3 meq/Kg (milliequivalents/gram) are deemed not suitable for salad oil applications and PV values above 10 meq/Kg are deemed to be unsuitable for human use because the measured PV value may be an early indicator of rancidity and free radical induced degradation. On the other hand, PV values taken alone do not adequately characterize such oils since a low PV value can also be associated with PUFA's that have already gone through the rancification process. Typical testing has revealed flax seed oil products sold for human consumption with observed PV's as high as 130 meq/kg also characterized with the odor associated with short chain aldehydes that make such oils “rancid” to olefactory senses.
Most raw seed based oils in common cooking and baking use, such as soybean, corn and canola seed oils naturally contain enough PUFAs making them unsuitable, without further processing, for use as cooking oils. Therefore unless such PUFA containing raw seed oils are hydrogenated to fully saturated triglycerides using hydrogen and a catalyst prior to their use in cooking applications, they are considered to be unfit for use as cooking oils. These oils are typically first isolated by, for example, expeller pressing the appropriate seed. The crude seed oil is then filtered to remove biomass. The resulting oil, containing significant levels of PUFAs, is then catalytically hydrogenated to reduce the PUFA content to levels suitable for use of the resulting oil in cooking applications. If the hydrogenation process is incomplete, however, the resulting mixtures are found to contain both undesirable heat labile PUFAs that quickly undergo rancification to small chain aldehydes in the resulting heated cooking oil as well as unsaturated trans-fatty acids which are believed to be detrimental to animal and especially human health.
Therefore, those skilled in the art will recognize the great difficulty in producing a shelf stable PUFA mixture wherein the PUFA content is as high as 70% wt/wt of the resulting seed extract from a natural seed source that then exhibits extraordinary room temperature stability.
Commonly assigned and copending patent application Ser. No. 12/419,321 discloses a Salvia hispanica L. derived seed oil extract composition of matter containing from 60-88% PUFAs in a ratio of from 3.1:1-3.3:1 of ALA to LA, 4-10% of C-18 mono-unsaturated fatty acid, 1-5% of C-18 saturated fatty acid and 4-8% of C-16 saturated fatty acid in a mixed triglyceride form stable at room temperature of 12-24 months containing a mixture of selected antioxidants. This chia derived composition has a very favorable ratio of ALA to LA (omega 3 to omega 6) of about 3.3:1 in one example. It is desirable to provide a composition of matter as a seed oil extract derived from other than chia and a method of manufacturing the seed oil that has equivalent or better PUFA content and ratios of ALA to LA and is shelf stable and exhibits room temperature stability.